1. Field of the Invention
This invention related to an integrated human patient simulator and methods of using same. In particular, this invention relates to a lung simulator for use in a patient mannikin capable of producing real time “breaths” during the inhalation and exhalation phases of a breathing cycle during a patient treatment simulation.
2. Background of the Invention
Currently, a new resident in a medical specialty will receive a very limited duration of didactic teaching about the principles of a particular medical procedure before delivering care to his/her first real patient. The resident is then faced with a new and unfamiliar environment while bearing the tremendous responsibility of caring for ill patients. Similarly, experience physicians who require continuing medical education, refresher courses, or familiarization with newly introduced and/or technologically sophisticated equipment or procedure do not have the opportunity for hands-on practice in a realistic environment without risk to a patient.
Human patient simulators, such as disclosed in U.S. Pat. Nos. 5,584,701; 5,769,641; 5,772,442; 5,772,443; 5,779,484; 5,868,579; 5,882,207; 5,890,908; 5,941,710; and 6,273,728, are used to address the above-mentioned deficiencies in medical, allied health care and veterinary education. The lung simulator described herein comprises a further embodiment of a patient simulator, particularly a self-regulating integrated human patient simulator. An example of a patient simulator, the Human Patient Simulatorm™ (HPS), is manufactured by Medical Education Technologies, Inc.
An integrated human patient simulator, such as the HPS, provides a clinician with valuable experiences that otherwise would not be possible outside of experiencing the actual medical situation in a clinical environment. The simulator allows the use of an interactive system to gain experience in managing both usual and unusual problems before the clinician actually cares for a patient. Further, with such simulators, clinicians can practice usual and unusual situations repetitively and try different interventions to achieve the best outcome.
In human organisms, the primary purpose of the lungs is to bring atmospheric air into contact with the blood. The process of moving gas in and out of the lungs is referred to as pulmonary ventilation, and the process of exchanging oxygen and carbon dioxide between air and blood is called respiration. A single breath or respiratory cycle consists of inspiration (inhalation) and expiration (exhalation). During a breath cycle, intrapulmonary pressure changes occur due to the expansion and contraction of the thoracic cavity, which prompts airflow in and out of the lungs.
In one prior art example, the “lung” of a simulator, such as used in the HPS, is comprised of at least one bellows and normally is comprised of a pair of bellows. One embodiment of a “bellows” lung simulator is disclosed in U.S. Pat. No. 5,584,701, which issued to Lampotang, et al., and which is incorporated by reference herein. The bellows are a physical representation of the lungs and movement of air to and from the bellows is similar to airflow in and out of the lungs when breathing. Typically, a piston is used to adjust the volume of the bellows such that the alveolar pressure inside the bellows is equal to a composite pressure determined by a lung model. The piston is normally adjusted by a manual pressure regulator or an electronic pressure regulator.
Using a “bellows” lung in a patient simulator causes several implementation and simulation problems. First, the bellows are typically large scale, extending upwards of 12 inches in diameter and 12 inches in height, which makes them difficult, if not impossible, to fit within the mannikin. Thus, they are normally attached to the mannikin by hoses that increase the anatomical dead space. Second, the bellow's material defines the compliance characteristic of the lung, which limits the compliance characteristic in the lung model, and which can by adjusted only within a limited range with the pistons. Third, the bellows are restricted to implementing a two-compartment lung model, which make it difficult to simulate complex higher order models, and which, due to the passive nature of the two-compartment lung model, do not provide a good simulation for spontaneous respiration. Finally, different sets of bellows must be used to simulate pediatric and adult profiles.
Another example of a known lung simulator for a patient simulator is a cylinder-piston mechanism, such as the servo lung simulator manufactured by IngMar Medical. This design calls for a cylinder with a computer-controlled mechanical piston that changes the internal volume of the cylinder to simulate breathing. The control of the piston is based on a two-compartment lung model. Because the volume of the cylinder must accommodate the largest tidal volume possible, the cylinder cannot fit within the mannikin. Furthermore, the piston creates mechanical problems and requires high maintenance for accurate simulations.
Yet another example of a known lung simulator is a slit/cam valve lung simulator. Here, a computer controls the opening of the slit/cam valve bases on a lung model. The slit/cam valve is used to pulsate gas flow to achieve only very simple flow patterns, such as, for example, cyclic flows.
Thus, there is a need for a lung simulator that is small enough to fit within the mannikin if desired; that allows the selection of any parameter values for the lung model; that can simulate both simple and complex breathing patterns; and that is flexible enough to simulate any type of physical profile, whether it be an adult or child, without changing any hardware components.